JP2007099005A - Torque detection device and electric power steering device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque detection device capable of lowering the height of its overall body and improving a carrying property in carrying a plurality of articles and an electric power steering device capable of further increasing an energy absorbing stroke. <P>SOLUTION: This torque detection device is devised to further increase the energy absorbing stroke of the electric power steering device constituted by installing a column free to absorb secondary impact energy by furnishing a holding ring 7 to hold a magnet collecting ring 5 arranged in an outer periphery of a magnet circuit forming member provided on a rotor on which torque is applied and to collect a flux and a detection part 6 to detect the torque applied on the rotor in accordance with the density of the flux collected by the magnet collecting ring 5 and having an attaching part to be attached on a stationary article on an outer peripheral part and providing a fitting groove into which a sealing ring is fitted on the attaching part on both of the end surfaces by making both of the end surfaces in the axial direction of the holding ring 7 roughly in parallel with each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a torque detection device that detects torque applied to a rotating body, and an electric power steering device that includes a torque detection device and an electric motor for assisting steering.

  As a torque detection apparatus, it describes in patent document 1, for example. The torque detection device of Patent Document 1 is juxtaposed in the axial direction so as to be separated from the outer periphery of a magnetic circuit forming member provided on a rotating body having an input shaft and an output shaft connected by a torsion bar. Are provided with two magnetic flux collecting rings that collect the magnetic flux generated by the magnetic flux collecting element, and a detector that detects the torque applied to the rotating body based on the density of the magnetic flux collected by each magnetic flux collecting ring.

  The torque detection device configured as described above is incorporated in, for example, an electric power steering device for a vehicle. The electric power steering apparatus includes the rotating body in which the input shaft is connected to a steering wheel, a cylindrical housing that accommodates and supports the rotating body, an electric motor for steering assistance that is connected to the output shaft through a speed reduction mechanism, A drive unit of an electric motor and a control unit connected to the detection unit and using a microprocessor, and the detection unit is caused by a twist generated in the torsion bar by applying torque to the input shaft by steering a steering wheel. The electric motor is detected and driven based on the detected torque.

In addition, when the torque detection device is incorporated into the housing, the entire torque detection device is inserted into the housing from one end of the housing, and is fixed inside the housing.
JP 2003-149062 A

  However, in the torque detection device configured as in Patent Document 1, since the entire torque detection device is inserted into the housing and fixed inside the housing, the torque detection device is placed in an appropriate position in the housing. There was a problem that it was difficult to perform the work of fixing to, and an improvement measure was demanded.

  FIG. 10 is an enlarged cross-sectional view of a part of the electric power steering apparatus provided with the improved torque detection device. Therefore, the applicant of the present invention provides a ring portion 102 that holds the magnetism collecting ring 100 and the detection portion 101, a mounting portion 103 that protrudes on one side in the radial direction of the ring portion 102, and the mounting portion 103. A torque detection device having a holding ring 105 having a flange 104 provided around the tip has been developed. The housing 106 of the electric power steering apparatus is provided with a through hole 107 that penetrates in the radial direction and an annular groove 108 that continues to the hole edge of the through hole 107, and a waterproof O-ring 109 is provided in the annular groove 108. By inserting, the torque detection device is inserted into the through hole 107 from the radial direction of the housing 106, the O-ring 109 is sandwiched between the annular groove 108 and the flange 104, and then the flange 104 is attached to the housing 106 with a small screw. I fixed it.

  When comprised in this way, the fixed workability | operativity of a torque detection apparatus can be improved. However, since the annular flange 104 protrudes from the attachment portion 103 of the retaining ring 105, the retaining ring 105 becomes bulky, and the transportability when plural pieces are transported is deteriorated. In addition, since the axial length of the housing 106 is increased by the length of the flange 104, an electric power steering apparatus in which a column capable of absorbing secondary impact energy is mounted on the housing 106 is The energy absorption stroke is shortened by an amount corresponding to the length of the flange 104.

  It is preferable to ensure the energy absorption stroke as long as possible to further improve the collision safety at the time of a frontal collision of the automobile. However, since the mounting position of the electric power steering device on the vehicle body is inevitably determined by the vehicle type, when the axial length of the housing 106 is increased, the lower column is fitted to and fixed to one end of the housing 106. When the upper column fitted to the column so as to be movable in the axial direction is moved to absorb the secondary impact energy, the amount of movement (energy absorption stroke) of the upper column with respect to the lower column is shortened.

  The present invention has been made in view of such circumstances, and a main object of the present invention is to further provide a torque detection device and an energy absorption stroke that can reduce the overall volume and improve the transportability when transporting a plurality. An object of the present invention is to provide an electric power steering device that can be lengthened.

  A torque detector according to a first aspect of the present invention is disposed around the outer periphery of a magnetic circuit forming member provided on a rotating body to which torque is applied, and a magnetic flux collecting ring for collecting magnetic flux generated by the magnetic circuit forming member, and the magnetic flux collecting device A detection unit that detects torque applied to the rotating body based on the density of magnetic flux collected by the ring, and an attachment unit that holds the magnetism collection ring and the detection unit and is attached to a stationary object on the outer peripheral portion And a holding ring having both end faces in the axial direction substantially parallel to each other, and seals a gap between the attachment portion and the stationary object at the attachment portion. It has an insertion groove into which the power sealing ring is inserted.

  The torque detector according to a second aspect is characterized in that the attachment portion has a flange between the both end faces.

  An electric power steering device according to a third aspect of the present invention includes the torque detection device according to the first aspect of the invention or the second aspect of the invention, and a through hole that penetrates the cylindrical portion that accommodates and supports the rotating body in the radial direction. A housing in which the attachment portion is attached in a state where the holding ring is fitted in the hole, a steering shaft connected to the rotating body, and an electric motor for assisting steering based on the torque detected by the torque detection device. It is characterized by comprising a controller for driving and a transmission means for transmitting the rotational force of the electric motor to the steering mechanism.

  An electric power steering apparatus according to a fourth aspect of the present invention is an upper column connected to a steering member, and a lower column that is fitted to the upper column so as to be capable of relative movement in the axial direction, and whose lower end is fitted and fixed to one end of the housing. The steering shaft is accommodated in the upper column and the lower column.

  According to the first aspect of the present invention, both end faces of the holding ring having the attachment portion are substantially parallel, and the both end faces and the attachment portion have fitting grooves, so that the volume of the holding ring can be reduced. . Accordingly, it is possible to improve the transportability when transporting a plurality.

  According to the second aspect of the invention, it is possible to easily fix the holding ring by the flange between the both end faces regardless of whether the both end faces are substantially parallel.

  According to the third invention, since the axial length of the housing can be shortened by the length of the flange of the retaining ring, when the column capable of absorbing the secondary impact energy is mounted on the housing, The energy absorption stroke can be lengthened by an amount corresponding to the flange. In addition, since the insertion groove is provided in the holding ring, when the holding ring is formed, the insertion groove can be formed. On the other hand, the housing does not need to be provided, and the cost of the housing is reduced. Can be reduced.

  According to the fourth aspect of the present invention, the amount of relative movement between the lower column and the upper column can be increased by the length of the flange of the retaining ring, so that the energy absorption stroke can be increased, and the collision safety at the time of a frontal collision of the automobile is improved. Can do.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. 1 is a cross-sectional view showing the configuration of a torque detection device according to the present invention, FIG. 2 is a perspective view showing the configuration of the torque detection device, FIG. 3 is a schematic exploded perspective view, and FIG. 4 is a diagram showing a rotating body rotated in one direction. It is explanatory drawing of the magnetic circuit which generate | occur | produces in a case.

  The torque detection device A is arranged on the outer periphery of the magnetic circuit forming member 4 included in the first rotating body 2 and the second rotating body 3 that are coaxially connected by the torsion bar 1 and arranged in the axial direction. The two magnetic flux collecting rings 5 and 5 that collect magnetic flux generated by the magnetic circuit forming member 4 and the torque applied to the first rotating body 2 are detected based on the density of the magnetic flux collected by the magnetic flux collecting rings 5 and 5. The detection unit 6, the magnetism collecting rings 5 and 5, and the detection unit 6, and the holding ring 7 having an attachment part attached to a stationary object such as a housing on the outer peripheral part, and the detection unit 6 with a conductor 8 And a connected detection circuit board 9. The magnetic circuit forming member 4 is disposed around the outer periphery of the first rotating body 2, the plurality of permanent magnets 41 and the outer periphery of the permanent magnet 41, and is fitted on the second rotating body 3. It consists of two fixed magnetic rings 42 and 42.

  The permanent magnet 41 is a multi-pole magnetized ring in which N poles and S poles are alternately magnetized in the circumferential direction, and is externally fixed to the outer peripheral portion of the first rotating body 2.

  The magnetic rings 42, 42 extend from the two annular plate portions 42 a, 42 a facing each other in the axial direction of the second rotating body 3 and the inner peripheral portions of the annular plate portions 42 a, 42 a so as to approach each other. Comb teeth 42b and 42b, and the magnetic flux density between the magnetic rings 42 and 42 is changed by rotating relative to the permanent magnet 41. The comb teeth 42b and 42b are arranged at equal intervals so as to alternately mesh with each other in the circumferential direction, and the magnetic rings 42 and 42 are molded with a synthetic resin material in a state where the comb teeth 42b and 42b alternately mesh with each other. It has become.

  The magnetism collecting rings 5, 5 extend radially outward from one place in the circumferential direction, have a cylindrical shape having convex pieces 51, 51 arranged on both sides of the detection unit 6, and the convex pieces 51, 51. The magnetic flux collects in The magnetism collecting rings 5 and 5 are formed by molding a magnetic plate such as an iron plate.

  The retaining ring 7 has a ring portion 71 having a through hole 71a corresponding to the inner peripheral surfaces of the magnetism collecting rings 5 and 5, and extends radially outward from the outer peripheral portion of the ring portion 71. It has a bottomed square tube portion 72 having a portion 72b, and is formed of a synthetic resin material. An attaching portion 72 b having flanges 72 c and 72 c is provided on the outer peripheral portion of the rectangular tube portion 72.

  Both end surfaces 7a and 7b in the axial direction of the holding ring 7 are substantially parallel, and the peripheral surface between the both end surfaces 7a and 7b is substantially U-shaped, in other words, both ends in the peripheral direction of the peripheral surface, in other words, Further, flanges 72c and 72c having insertion holes 72d and 72d for inserting a small screw project from both side portions 7c and 7c between both end surfaces 7a and 7b, and an attachment portion 72b extends from the base of the flanges 72c and 72c. An annular insertion groove 73 is provided over the entire circumference. A sealing ring 10 made of an O-ring that should seal the gap between the attachment portion 72b and the stationary object is inserted into the insertion groove 73. The fitting groove 73 is formed when the holding ring 7 is formed.

  The through hole 71a and the accommodating portion 72a communicate with each other through a communication hole 71b. The magnetism collecting rings 5 and 5 are fitted and fixed to the ring portion 71, and the convex pieces 51 and 51 of the magnetism collecting rings 5 and 5 are connected to the communication hole. 71b. The detection circuit board 9 is attached to the housing part 72a with a small screw, and the lid 11 from which the conductive wire from the board 9 is taken out is attached to the open end of the rectangular tube part 72 with a small screw or the like. It is done.

  The detection unit 6 is composed of a Hall element whose electrical characteristics (resistance) change due to the action of a magnetic field, and the detection signal changes according to the change in magnetic flux density generated between the convex pieces 51 and 51 of the magnetism collecting rings 5 and 5. The detection signal is given to the detection circuit board 9. In addition to the Hall element, the detection unit 6 may be a magnetosensitive element whose electrical characteristics (resistance) change due to the action of a magnetic field, such as a magnetoresistive element (MR element), and is not limited to the Hall element.

  5 is a partially enlarged cross-sectional view showing an example in which the torque detection device is used in an electric power steering device, FIG. 6 is a perspective view showing a relationship between the torque detection device and a housing, and FIG. 7 is a method for assembling the housing into the housing. FIG. 8 is a cross-sectional view of the torque detection device portion, and FIG. 9 is a cross-sectional view of the entire electric power steering device.

  The torque detection device A configured as described above is used, for example, in an electric power steering device for a vehicle. This electric power steering device has a steering shaft 20 whose upper end is connected to the steering member and whose lower end is connected to the first rotating body 2, and a transmission shaft 21 that is coaxially connected to the steering shaft 20 by the torsion bar 1 (second A rotating body 3), a housing 25 surrounding the first rotating body 2 and the transmission shaft 21, and rotatably supporting the first rotating body 2 and the transmission shaft 21 by three bearings 22, 23, 24, The steering assisting electric motor 26 attached to the housing 25, the speed reduction mechanism 27 for transmitting the rotational force of the drive shaft of the electric motor 26 to the output shaft 21, the torque detection device A, and the torque detection device A A control unit 28 using a microprocessor connected to the detection circuit board 9 and a drive circuit of the electric motor 26, and a lower column 2 in which the lower end is externally fitted to the upper end of the housing 25 and accommodates the steering shaft 20. When being fitted to allow relative movement in the axial direction on the lower portion column 29, and an upper column 30 to accommodate supporting a steering shaft 20.

  A housing 25 as a stationary object attached to the vehicle body has a coupling cylinder portion 25a at the upper end, a cylindrical portion 25b surrounding the first rotating body 2 and the transmission shaft 21, and an outer peripheral portion of the cylindrical portion 25b. A projecting seat 25c for mounting the holding ring 7 and a through hole having a rectangular cross section for passing through the cylindrical portion 25b in the radial direction and arranging the magnetic flux collecting rings 5 and 5 in the cylindrical portion 25b. It has a hole 25d and a fitting groove 25e that is continuous with the through hole 25d and curves in correspondence with the ring portion 71 of the holding ring 7. The mounting seat 25c is disposed at two positions facing the flanges 72c and 72c. The mounting seat 25c is provided with one screw hole 25f and 25f, respectively, and is inserted into the insertion holes 72d and 72d of the flanges 72c and 72c. The holding ring 7 is attached to the housing 25 by screwing the inserted small screw 12 into the screw holes 25f, 25f.

  The coupling cylinder portion 25a is disposed in the vicinity of the through hole 25d, and the bearing 22 is fitted and fixed inside, and the lower column 29 is fitted and fixed outside.

  Between the fitting portions of the lower column 29 and the upper column 30, a cylindrical shape is provided, and an impact energy absorbing member 31 for absorbing secondary impact energy is provided. A bearing 32 supporting 20 is fitted and held. Further, a transmission ring 33 that is in contact with the upper surface of the bearing 32 is fixed to the steering shaft 20, and secondary impact energy applied to the steering shaft 20 is transmitted from the transmission ring 33 and the bearing 32 to the upper column 30, and the impact energy. The upper column 30 is moved in the axial direction with respect to the lower column 29 while being absorbed by the absorbing member 31.

  The retaining ring 7 inserts an annular portion 71 into the cylindrical portion 25b from a through hole 25d that penetrates the cylindrical portion 25b of the housing 25 in the radial direction, and engages the annular portion 71 with the fitting groove 25e, thereby collecting magnetism. The positions of the rings 5 and 5 in the cylindrical portion 25b are determined, the sealing ring 10 comes into contact with the inner surface of the opening edge side of the through hole 25d and seals, and the flanges 72c and 72c of the holding ring 7 are attached to the attachment seat 25c. Is done. After attaching the holding ring 7, the first rotating body 2 and the transmission shaft 21 are inserted into the cylindrical portion 25 b from the axial direction of the housing 25, and the permanent magnet 41 and the magnetic ring 42 are connected to the magnetism collecting rings 5, 5. Arranged inside.

  The steering shaft 20 has an upper shaft 20a and a lower shaft 20b that are connected by an impact energy absorbing member 34 so as to be relatively movable in the axial direction. Secondary impact energy applied to the upper shaft 20a is transferred to the impact energy absorbing member. The upper column 30 is moved in the axial direction with respect to the lower column 29 while being absorbed by 34.

  In the electric power steering device configured as described above, both end surfaces in the axial direction of the holding ring 7 of the torque detection device A are substantially parallel, and the fitting groove 73 is provided in the attachment portion 72b on both end surfaces, Since the sealing ring 10 is fitted in the fitting groove 73, the attachment portion 72b of the holding ring 7 is sealed by the sealing ring 10 without providing a sealing fitting groove in the through hole 25d of the housing 25. can do. In addition, since there is no need to provide a sealing insertion groove in the through hole 25d of the housing 25, the housing 25 is provided with an insertion groove around the distance H between one end of the housing 25 and the stepped portion. The length can be shortened compared to the case where the sealing ring is sandwiched between the flanges. Accordingly, the amount of movement (energy absorption stroke) S of the upper column 30 with respect to the lower column 29 in the axial direction is such that the housing 25 is provided with a fitting groove, and the sealing ring is sandwiched between the peripheral flanges. The collision safety can be further increased at the time of a frontal collision of an automobile. Moreover, since it is not necessary to provide the sealing insertion groove in the housing 25, the cost of the housing 25 and, consequently, the cost of the electric power steering device can be reduced.

  Further, in the electric power steering apparatus, the detection unit 6 detects the rotational torque applied to the steering shaft 20 by operating the steering member by the torsion generated in the torsion bar 1, and the detection torque is converted into a voltage signal by the detection circuit board 9. Thereafter, the electric motor 26 is driven and controlled by the instruction signal output from the control unit 28 and output from the control unit 28, and the transmission shaft 21 rotates via the speed reduction mechanism 27.

  In addition, you may use the torque detection apparatus A which concerns on this invention for apparatuses other than an electric power steering apparatus other than using an electric power steering apparatus.

It is sectional drawing which shows the structure of the torque detection apparatus which concerns on this invention. It is a perspective view which shows the structure of the torque detection apparatus which concerns on this invention. It is a typical exploded perspective view of the torque detector concerning the present invention. It is explanatory drawing of the magnetic circuit which generate | occur | produces when a rotary body rotates to one direction. It is a partial expanded sectional view which shows the example which used the torque detection apparatus for the electric power steering apparatus. It is a perspective view which shows the relationship with the housing of a torque detection apparatus. It is explanatory drawing which shows the assembly method to a housing. It is sectional drawing of a torque detection apparatus part. It is sectional drawing which shows the whole structure of the electric power steering apparatus which concerns on this invention. It is sectional drawing to which some electric power steering devices provided with the improved torque detection apparatus were expanded.

Explanation of symbols

A Torque detection device 2 First rotating body (rotating body)
3 Second rotating body (rotating body)
DESCRIPTION OF SYMBOLS 4 Magnetic circuit formation member 5 Magnetic collecting ring 6 Detection part 7 Holding ring 72b Attachment part 72c Flange 73 Insertion groove 10 Sealing ring 20 Steering shaft 21 Transmission shaft (Transmission means)
25 Housing (stationary object)
25b Cylindrical part 25d Through hole 26 Electric motor 28 Control part 29 Lower column 30 Upper column

Claims (4)

  Based on the magnetic flux collecting ring arranged around the outer periphery of the magnetic circuit forming member provided on the rotating body to which torque is applied and collecting the magnetic flux generated by the magnetic circuit forming member, and the density of the magnetic flux collected by the magnetic collecting ring A torque detection device comprising: a detection unit that detects torque applied to the rotating body; and a holding ring that holds the magnetism collecting ring and the detection unit and has an attachment portion attached to a stationary object on an outer peripheral portion. The holding ring has axially opposite end faces that are substantially parallel to each other, and a fitting ring into which a sealing ring for sealing a gap between the attachment part and the stationary object is inserted into the attachment part. A torque detection device comprising:   The torque detector according to claim 1, wherein the attachment portion has a flange between the both end faces.   A torque detection device according to claim 1 or 2, and a through-hole penetrating in a radial direction through a cylindrical portion that accommodates and supports the rotating body, and the holding ring is fitted in the through-hole. A housing to which the attaching portion is attached, a steering shaft connected to the rotating body, a control unit for driving an electric motor for assisting steering based on the torque detected by the torque detecting device, and a rotational force of the electric motor. An electric power steering apparatus comprising: a transmission unit that transmits power to the steering mechanism.   An upper column connected to the steering member; and a lower column fitted to the upper column so as to be capable of relative movement in the axial direction and having a lower end fitted and fixed to one end of the housing. And an electric power steering device according to claim 3 housed in the lower column.

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